Luke's lightsaber changes drastically in "Return of the Jedi". This is because during "The Empire Strikes Back" Luke's trusty lightsaber is lost during a duel with Darth Vader. That means that Luke had to construct a brand new lightsaber. Unlike the other lightsabers used in the Star Wars Trilogy Luke's "Return of the Jedi" lightsaber was not made from pre-existing parts. His new lightsaber was completed machining from metal. During a deleted scene from "Return of the Jedi" Luke can be seen making his lightsaber in Obi Wan Kenobi's hut. Evidently Luke uses plans that Obi Wan used to make his. Luke's "Return of the Jedi" lightsaber and Obi Wan's "A New Hope" lightsaber have the same basic design. Things to note about Luke's lighsaber is that it uses a Tri-ring to attach to a belt unlike the usual D-ring. It also uses a circuit board.